Unipolar and bipolar surgically implanted temporary heart wires are well known in the art, some examples of which may be found in the issued U.S. Patents listed in Table 1 below.
TABLE 1 ______________________________________ Prior Art Patents U.S. Pat. No. Title ______________________________________ 3,035,583 Conductive Sutures 3,125,095 Flexible Stainless Steel Sutures 3,664,347 Electric Heart Stimulation Method and Electrode 3,949,756 Sutures with Notch Near Needle-Suture Junction 4,010,756 Heart Pacer Lead Wire with Break- Away Needle B1 4,010,756 Heart Pacer Lead Wire with Break- Away Needle 4,054,144 Short-Crimp Surgical Needle 4,338,947 Positive Fixation Heart Wire 4,341,226 Temporary Lead with Insertion Tool 4,442,840 Electrical Connector Apparatus and Method for a Temporary Cardiac Pacing Wire 4,444,207 Method of Anchoring a Temporary Cardiac Pacing Lead 4,530,368 Temporary Bipolar Pacing Lead 4,541,440 Bipolar Epicardial Temporary Pacing Lead 4,553,554 Electrical Lead and Method for Temporary Cardiac Pacing 4,630,617 Heart Pacer Lead Wire with Pull-Away Needle 4,633,880 Surgical Electrode 4,693,258 Surgical Electrode for Cardiac Pacing and Monitoring 4,972,833 Epicardiac Pacing Lead 5,217,027 Temporary Cardiac Lead 5,241,957 Bipolar Temporary Pacing Lead and Connector and Permanent Bipolar Nerve Wire 5,314,463 Bipolar Nerve Electrode 5,350,419 Cardiac Pacing Lead 5,423,876 Intramuscular Lead Having Improved Insertion ______________________________________
All patents listed in Table 1 hereinabove are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, many of the devices and methods disclosed in the patents of Table 1 may be modified advantageously by using the teachings of the present invention.
Surgically implanted temporary heart wires for use as heart pacer and monitoring electrodes are well known in the medical profession. In general, such a heart wire is constructed of a number of fine, stainless steel wires twisted together to form a single, flexible, multifilament electrode wire. The major portion of the wire is typically insulated with a polyethylene, polytetrafluoroethylene, silicone, nylon, or other suitable electrically nonconductive and biocompatible materials, with a short length of wire at either end left uninsulated.
To one uninsulated end of such an electrode wire there is generally attached by swaging or other means a fine curved needle for piercing the heart tissue to place the uninsulated end of the electrode in the myocardium or epicardium. At the other end of such an electrode wire there is generally affixed a Keith-type cutting needle for piercing the thoracic wall to lead the electrode to an outer point for connection with the pacemaker. Once the electrode has been properly positioned, the curved needle and the Keith-type needle are typically clipped off and the uninsulated end of the electrode is ready for attachment to a pacemaker or monitoring device.
Some prior art unipolar heart wires have break-away Keith-type needles attached to their proximal ends, where no clipping is required to remove the needle from the heart wire. Other prior-art Keith-type breakaway needles require the use of, or most preferably employ, an external adapter or transition box for breaking the needle in the appropriate location and facilitating attachment of electrical conductors in the lead to an external electrical apparatus. See, for example, the bipolar heart wire and corresponding external connector disclosed in U.S. Pat. No. 5,241,957, where the external connector is required to establish electrical connection between an EPG or PSA and the heart wire.
Many known heart wires are characterized in having one of the two following disadvantages. First, when some known unipolar heart wires are used in applications requiring two electrodes, two different, separate heart wires must be attached to the heart in two separate procedures. Attaching two such heart wires consumes valuable time at a critical stage in heart surgery. Second, when some known bipolar heart wires are used, the needle attached to the proximal end of the heart wire for piercing the transthoracic wall must be clipped off with a scissors or other tool, and pin connectors must be attached to the resulting bare separate wires for establishing electrical connection to an external pacemaker or external electrical apparatus. These steps of needle removal and wire attachment are separate, time consuming acts, and also occur at a critical stage in heart surgery. Moreover, upon repeated attachment, removal and reattachment, the ends of the stainless steel wire may fray and become difficult to work with.
What is needed is a heart wire that attaches easily and quickly to the heart but which also has convenient, easy-to-use connectors disposed between the proximal end of the heart wire and an external pulse generator (EPG), pacing system analyzer (PSA), defibrillator or other such external electrical apparatus. Most preferably, the heart wire should not require substantial electrical or mechanical manipulations by the surgeon, should be comfortable to the patient, and should establish secure and reliable electrical contacts. Finally, the heart wire should be reasonably economical to manufacture.